From: Seth Jenkins sethjenkins@google.com

stable inclusion from stable-v5.10.169 commit c261f798f7baa8080cf0214081d43d5f86bb073f category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9K29F

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

commit 81e9d6f8647650a7bead74c5f926e29970e834d1 upstream.

Commit e4a0d3e720e7 ("aio: Make it possible to remap aio ring") introduced a null-deref if mremap is called on an old aio mapping after fork as mm->ioctx_table will be set to NULL.

[jmoyer@redhat.com: fix 80 column issue] Link: https://lkml.kernel.org/r/x49sffq4nvg.fsf@segfault.boston.devel.redhat.com Fixes: e4a0d3e720e7 ("aio: Make it possible to remap aio ring") Signed-off-by: Seth Jenkins sethjenkins@google.com Signed-off-by: Jeff Moyer jmoyer@redhat.com Cc: Alexander Viro viro@zeniv.linux.org.uk Cc: Benjamin LaHaise bcrl@kvack.org Cc: Jann Horn jannh@google.com Cc: Pavel Emelyanov xemul@parallels.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Wang Hai wanghai38@huawei.com --- fs/aio.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/fs/aio.c b/fs/aio.c index 0063e4bc0aad..00641a1ad0b3 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -335,6 +335,9 @@ static int aio_ring_mremap(struct vm_area_struct *vma) spin_lock(&mm->ioctx_lock); rcu_read_lock(); table = rcu_dereference(mm->ioctx_table); + if (!table) + goto out_unlock; + for (i = 0; i < table->nr; i++) { struct kioctx *ctx;

@@ -348,6 +351,7 @@ static int aio_ring_mremap(struct vm_area_struct *vma) } }

+out_unlock: rcu_read_unlock(); spin_unlock(&mm->ioctx_lock); return res;